Means for investigating ether propagation paths



0, 1943. N. E. LINDENBLAD ET AL 2,326,662

MEANS FOR INVESTIGATING ETHER PROPAGATION PATHS Filed NOV. 29, 1941 7'0RECE/ l/EK INVENTORS N/LS E. L/A/DENBL/IO BY JAM F/NCH W ATTORNEY jAnother object of the present ;inve

provision of an antennastructure forjdeterminle'of arrival of received.radio signalfis reflected- "fro ,MEANS FOR;

" @Niis Eplai i Corporation wax-e {mama fn emt f 29, le ii se iainogifzoes The present invention relates tofdireotional f antennasparticularly adapted to .the' measurement of the vertical arrival angleof radio signals over ether propagation paths] An object of the presentinvention a direct and. accurate mea's of arrival of radio signalsfing'the vertical ang signals.

Still another 'ohject of the presentirivention V is to facilitateinvestigation o1v the propagation paths of high frequency radio 5 atransmitter Vandareceiver.

ev foregoing objects; and othe and equally timed. iinpul'ses'ffofradiqfrequency energy from a tran's niitter and receivingr thse impulsesona'pairflofjloopantennas-arrangedt ord er'of 100mm- /'o of asecondi- Iv The present. invention toward the terrninationof therangles with themsnicwme' Emmi fidenblad, "Roeky-Point; and James Finch,*i3ast,Rookaway,N. figlassignors to' Radio" "of Ameriea, a e poration cf: Dela V V V isthe operation of an antenna structure which provides urement cran anglention is the 1 rswhich may appear from thejfollowing detailedjdesc'riptio ng v are attained, in accordance with. the principles ofthe present invention, byitransniitting shortl rn'iine their particular(1119] tion' is 3 partiqularly designed for a frequencyrangeofj fromthree 't'o twenty five meg acycles though its operation is notlim-fiitecl tothisrang'ef .TIfhe impulses may hi'of the secondsinler'ie'thandspaced;

'riong g'ngns (o1'.25c-"-11 I c v dersto'od' by- 'reference' to p thefollowing- -V.deta1le d escr t n, w icnjisiacco pa i di'by a dra n inwhich: Figure Ifillustratesl a 's'iclefview {of -an antenna constructedaccording tqthez-riresent invention, while Figure 2 "s a front Viewthereo jInQFigurelQ referenoe 'aracters I and}ilfin 'dicateaypairof loopantennas '.;QLoopantennas v I and12 areipreferahly .nietalenclosed loopsinsulated wire;- t'l'iefmtall enelosure 5- d s 1; continuous at theuppermost "point so "a not d act as a-s'hort circuit oni th e' WindingTh vl ar :supporteclj on a e flwhich, 'u iqrt sl r K the flarg'erjfparts of the stlll lCtule re 15 ably? madepfi insulated aterial; inorder-not to? distort:cthe freceived,s

tern -,LoopsJfand'.2Qareisupported by projeo V itions' eiaringsvaboutivhioh zth'e hich "serve as l, b

7 loop can1iberotated; The y lo are rotated by 2 me'a f arms fijand'fiwhich er' byjconnectingrod l,

' rod 7 Bare so pro'portion'e when: rnember- 6 isfr'otat'ed. tation" of.loop 2 1ofop2 009' l Wi lia o" W111 same direction thus planes of theitwozloo parallel. f j

rotatably mount ed on me '3" 8, rigidly attached; th V a v V V I armsand j 6; are caused drum; Ii] is; rotated and S11 r are equal inam'ountlfand i A 11mm l -21 5 se ure horizontal at which the'variouselements of the I a received signal arrive. It is "well known that Ta-.5

dio signals'of theserfrequenc'ies arrivefover moref.

than one major path, 'theldiffe'rent 'znajor' paths; being determin edbythe number of timesr the I m thefionized 'layersr in the upperatmosphere. In the application'o'i received signals are impressed-oiaxis of a cathodefray oscilloscope: Asw'ep ire quency of the frequeno'yo'f pulse transmission is impressed on thewhorizontal axis. Thus 7 a'pulse appears on the oscilloscope 'screen-foreach'lma 7 jor ether path.While keepingith f oscilloscope .1

soreen ine-view the operator orientsthe' loops so that one of thesepulses ,goes .to a minimum From the orientation. of these loops:toobtain fs'ult theiangle ofia'rrival' o'f'this pulse canine-determined'7 1Q a w e r The present invention illfhe'n'iore full ini th e presentinvention the ,thefv ertical;

cause. drum fi flflto rotate" in' the ,oppo' site'cdirection by anequa1a g1.-,

The connecting; rod} ,and arm linkage, rotates). V loops} andlthrough-fthe same-angle a's fdr uni" I34; flhllSQWhen ir'ameffiislmoved backto} position a's'jindioated:byJS'Qth loops 7' qual amountiof rot tilt forward by, an, r "indicated by lines" V ne 21. Thus, ifthe icul arl p H brated in degrees and normally so arrangedlthat thereading is zero when the frame is vertical," 7

1' signalielcments'mair tensed;

as shown in Figure 2. f Loops .I 'and 2,- have transmission lines 18 and13 connected thereto and are connected in series in phase opposition 5's s r ,fram'eadapted to be piv'oted in a vertical plane of a propagationpath of a radio signal about an I at junction 20,to,transmission line2!, which'is connected to receiving equipment; The receiv 7 ingequipment may include a: cathode rayoscilloscope having vertical andhorizontal deflect--;-

mesa i a but :inthe opposite direction tofthe rotation ofsaid'supporting means and means for connecting signal transducer means.

h 3.,A directional antenna. system including 2.

axis atone end adjacent to the earths surface, a pair of rotatable loopantennas supported at ing meanszassociated therewith. [The received 110"spaced points on said frame, means for rotating signals are applied tothe verticaldeflection means so' that a vertical pulse appears on thelines traced across the oscilloscope screen'for; each ether. pathtraversed by the receivedrsigei f- 1. Hal.

ably the same as the frequency of pulse transmission. Y

While keeping the oscilloscope screen in view; the operator orients theloops by swinging frame" 3' so that one ofthe pulses goesto a minimum.20

occurs eachloop receivesridenticai radio frequeneysignals-as-regardeibotn amplitude and phaseas will occur" when loopsand" 2; are I both; normal to thewave front-oi a: particular "receivedsignal, for example, 'thatindicated by 5 arrow A1; A: at an angle o withrespect'to the r horizontal} [Due to the" inherent directional effect ofthe loops neither loopiis responsive to radio 1 signals arriving along aline at rightaneles to the.

planes of the loops. Thusia si naloornponeht 3owhich'is reflected upfrom the eartn'i'rorn a short distance in front of the ioop uchasthatlndicated by'a'rrows CLQCE at an ahgieo', arrives right angles, tothe loops and. thereforefsets up 7 no voltagestherein. Ifthetraee on thecathode. 35'

rayi scilloscopescreen indicates thatja "-partied lar-signal impulseisyreoeivedo er a plurality of; different p ths theeri'g'i of arrival ofeachoithe pulses may p successiveiy' measured by sueceseiveiy adjustingthe angle or frame Qiifitil 4o 7 each pulse irisiicce'ssion'goes to aminimum;-

no particular means for ti'itiheirame 3 have vhll "befsatisfactory forthis purp se. v more; itis oohsiciered within, the stop 'rar gement tomaintain the loops I I ahdizi'n the relative" positions and, at th eirelative angles as described iabove. Also; aiiy cievice other than theD" ixiavertioaiiplane'oi a propagation pathof a radio signal, a'pair ofspaced rotatable loop ane' tennas supported on'said frame andfhavingtheir oscilloscope described io difierehtiatiog bet e n; signaljelementsarriviiife tunes j'f a iid for detecting the intensit r: th e Whiie haveparticularly a dQde-j scribedsev'eral embodiments of ourinventioifi,..it 5T tube clearly understood thatou'r invention-is not,

limited thereto ibot that modifi ations be made within thezscope of'thje in'vehtiohi weclaim; e i

l. A directionaltantenna,system I V elongated frame adapted to hepivoted about an.

pail? of loop antennas rotatably mounted on sup porting means, said"supp rtinggn een ,beingj' adapted to'be rotatedin the p aneof apropaga-f f,

tion' path of a radioisignai," ineahs fOlfwSilXlllltaiiecflislyrotating-said loops theflsaineamount 3 air of loop antennas rotatabiymounted on suporting means, saidsupporting neans 'peing, I adaptedto berotated in the plane of afpropaga- 7 tion: path of a radioeignaLmeansfor simulta-C The horizontal sweep frequency is prefer- 15.at slightly different-' staid loops'the'sarne amount as, but in anopposiiidirection to, the rotation of said frame about its axisdirectional antenna system including a frame adaptedtobe pivoted in avertical plane of a propagation path of a radio signal about an axis atone end adjacent to the earths surface, a

pair of rotatable loop antennas supported at spaced: points on saidframe means responsive to a movement of said frame about said axis forrotating said loopsthe same amount' as, but in an opposing direction to,the rotatioziof' said frame about its axis. r p

5. A, directional antenna system including a ai iis at one end adjacentto the earth's surface, a

pair of rotatable loop antennas supported] at spaced points on saidfrarne, means for rotating said loops the same amount aabut in. anopposing direction to, the rotation of said frame about its axis andmeans forcoupling said loops in series inphase opposing relationship tosignal trans-ducermeans; I

elongatedframeadapted to be pivoted about an axis' at' onie end adjacentto the earths surface in a verticalplane of a; propagation path: of a" 1elongated frameiadapted to be piv ted about an axisat one endr adjacentto the earth?s,surface 1 axes of rotation parallel toithepiv'oting'axis'of saidyframe; means: for causing said loops to rotate'inI'e SpOHS I tO the motion of said frame about itsaxis an amount equal tothe movement of said frame but in the opposite direction thereto, and

;means for coupling saidloops in series in phase 8; Adirectiohalantennasystem including an axis at one end adjacent tojtheearth's surface in a vertical plane of a propagation path of a radiosignal, a pair of. spaced rotatable loop anaxes of rotation parallel tothe pivoting a'iiis of said frame,"me ans for causing said loops torotate infresfponse to the 'motionof said frame about its axis an amountequal'to themoven'ient of vsaid a Aclil-eetio al' 'antenha system.including 0"frame, but in the opposite direction thereto, and. means forcoupling said loops in series inpha'se V opposing relationship tosignal'tians'ducer'means H and means for determining the angle whichsaid frameforrns with respect to the earths surface.

neoiisly rotatingsaidloops tlie'sameiarnount as; 75:" 9.; Adirectionalantennasystem including an saidloopg-in a phase opposing relationship toframe adapted to bepivoted in a veitical plane of'apropagation partner aradio signal about an 6. A' directional antenna system including an.

.of saidframe but. in the'opposite dire tion there- 7 F '7. Adirectional antenna s'ystein including, an

opposing relationship to signal transducer means.

tennassupportedjon said frame and having their elongated franie adaptedto be pivotedf magnettothejeartl i s sur face; apair of'rota at 1 an theearth's surface,--a pairof roiqatableioop anq tric'withftheaxis of, saidframe and rfixedfin -iio'si the earth s surface, a'iiair of rotatableloop. ail-"15 theearthsjsurfaca'a paii'ldf otaitable floop an concentricwiths theaxis of said frame, ;a second 7 t icwith"t1ie axis ofsaid-flame and fig'zedin po drum inounted for rotation on said frame,fineans I for coupling said loops andsaidjsecond'yzlrum'e to:ond"drum;'tn ounted"foi7 radiation o'f jsai'd 'frar'ne,;* gather foi'equal simultaneous rotatiohinliikm same direction and acablejpassingfafound andattached to sai'd'druins whereby a moflement of,a',326,662' .j i

tical plane about an axis atone end adjacent to ten'na'sspaded-alongf'said frame; la difum 0 gen tennasspacedsalong said frame,a dfljimnoncen- I; tioriwith-respect toithet-eartl s surfaeeja Sbontric' withthefakisof said frame and fixed in po'si "5 dijum mountedfor"'rqi aiEiOI ol fsaidi fi amegfrneans tion with respect to theearthssurface,-a second; 1 fo c'oup ling' said loops andsaid sebond 'drum'todrum mounted for. rotation on said-frame, means] i I g'ether for equal:simultaneous; rotation vi g-[the for coupling said loops and saidsec0nd-drum1t I saine' directionl 'afcable gpas'sing around". nd'fatgethei for equal simultaneous rotation in i the tachedtofsaiddrums.and-means for coupling sa'iw same direction and azeable passingaround ,and 110i loop antennas inserisand intapiiase liposihg, attachedto said drums, V j i ,f a i f relationship;to"signa1 transducerimean 10.A directionalantennasystem including'an if 1 4 d 'a a's st m-inelongated frame adapted' to be'pivotedi in ayerelongated frame,.adap evto"bepivoted} yeif tical' plane about an axis at one end 'adjacentftortical plane' ia'b'outfanaxis-atone endgadjacent -t itennasspaced alongsaid -franrie, afixd dr'um- 'fennassbacedl along said frame, a d m c'once n ltio w t ire' ac to 5 he'iearths :s r a c U r I xneansf ior couplingsaid :loops and said; second rum 'togethenforjequal simultaneous oigatio"F iretiom;a;cahlfi?assing- 3 :61-3 I v I I V l aidfdrums' and.nieansi'for coup loop antennas about their axes of rotation; 1 l saidloop" antennas in}fd} 1J ,-8 QPPOSing 1 11. A directional antenna systemincludin n 5' s'hi tfosignal'ti ansduqenmeans j elongatedfiame adaptedtobefpivot ed in al:ve rj tical glariefaboutah.axis at'oneendeadjacenJAMS LFFINCH;

said frameabout its axis 'Eauses'rotation of 'said'

